Simple. It's a scarce product. There are only 21 million bitcoins and if you can get a full bitcoin then you're gonna be amongst the 1% at some point in your life.
It could go to zero but it is more probable it will go to a million before that
true as you said, bitcoin is a rare product, try to buy it because everyone believes everyone can invest in crypto, no exception, if we keep paper money, it is easy to be hacked and stolen, if we keep it at home in case of theft all that it will be very easy for them to take all our money, but if we invest in bitcoin it is not easy for people to steal our crypto, because it is very difficult for them to open our security code, even if they manage to steal our software, not necessarily they can take our assets, because only we know the key